Unique P?Co?N Surface Bonding States Constructed on g‐C3N4 Nanosheets for Drastically Enhanced Photocatalytic Activity of H2 Evolution

Developing high‐efficiency and low‐cost photocatalysts by avoiding expensive noble metals, yet remarkably improving H₂ evolution performance, is a great challenge. Noble‐metal‐free catalysts containing Co(Fe)? N? C moieties have been widely reported in recent years for electrochemical oxygen reduction reaction and have also gained noticeable interest for organic transformation. However, to date, no prior studies are available in the literature about the activity of N‐coordinated metal centers for photocatalytic H₂ evolution. Herein, a new photocatalyst containing g‐C₃N₄ decorated with CoP nanodots constructed from low‐cost precursors is reported. It is for the first time revealed that the unique P(δ^?)? Co(δ⁺)? N(δ^?) surface bonding states lead to much superior H₂ evolution activity (96.2 µmol h^?1) compared to noble metal (Pt)‐decorated g‐C₃N₄ photocatalyst (32.3 µmol h^?1). The quantum efficiency of 12.4% at 420 nm is also much higher than the record values (≈2%) of other transition metal cocatalysts‐loaded g‐C₃N₄. It is believed that this work marks an important step toward developing high‐performance and low‐cost photocatalytic materials for H₂ evolution.     

Ice‐Assisted Synthesis of Black Phosphorus Nanosheets as a Metal‐Free Photocatalyst: 2D/2D Heterostructure for Broadband H2 Evolution

A 2D/2D heterojunction of black phosphorous (BP)/graphitic carbon nitride (g‐C₃N₄) is designed and synthesized for photocatalytic H₂ evolution. The ice‐assisted exfoliation method developed herein for preparing BP nanosheets from bulk BP, leads to high yield of few‐layer BP nanosheets (≈6 layers on average) with large lateral size at reduced duration and power for liquid exfoliation. The combination of BP with g‐C₃N₄ protects BP from oxidation and contributes to enhanced activity both under λ > 420 nm and λ > 475 nm light irradiation and to long‐term stability. The H₂ production rate of BP/g‐C₃N₄ (384.17 µmol g^?1 h^?1) is comparable to, and even surpasses that of the previously reported, precious metal‐loaded photocatalyst under λ > 420 nm light. The efficient charge transfer between BP and g‐C₃N₄ (likely due to formed N? P bonds) and broadened photon absorption (supported both experimentally and theoretically) contribute to the excellent photocatalytic performance. The possible mechanisms of H₂ evolution under various forms of light irradiation is unveiled. This work presents a novel, facile method to prepare 2D nanomaterials and provides a successful paradigm for the design of metal‐free photocatalysts with improved charge‐carrier dynamics for renewable energy conversion.     

Synthesis of Leaf‐Vein‐Like g‐C3N4 with Tunable Band Structures and Charge Transfer Properties for Selective Photocatalytic H2O2 Evolution

Photocatalytic H₂O₂ evolution through two‐electron oxygen reduction has attracted wide attention as an environmentally friendly strategy compared with the traditional anthraquinone or electrocatalytic method. Herein, a biomimetic leaf‐vein‐like g‐C₃N₄ as an efficient photocatalyst for H₂O₂ evolution is reported, which owns tenable band structure, optimized charge transfer, and selective two‐electron O₂ reduction. The mechanism for the regulation of band structure and charge transfer is well studied by combining experiments and theoretical calculations. The H₂O₂ yield of CN4 (287 µmol h^?1) is about 3.3 times higher than that of pristine CN (87 µmol h^?1), and the apparent quantum yield for H₂O₂ evolution over CN4 reaches 27.8% at 420 nm, which is much higher than that for many other current photocatalysts. This work not only provides a novel strategy for the design of photocatalyst with excellent H₂O₂ evolution efficiency, but also promotes deep understanding for the role of defect and doping sites on photocatalytic activity.     

Engineering the Photocatalytic Behaviors of g/C3N4‐Based Metal‐Free Materials for Degradation of a Representative Antibiotic

Graphitic carbon nitride (g/C₃N₄) is of promise as a highly efficient metal‐free photocatalyst, yet engineering the photocatalytic behaviours for efficiently and selectively degrading complicated molecules is still challenging. Herein, the photocatalytic behaviors of g/C₃N₄ are modified by tuning the energy band, optimizing the charge extraction, and decorating the cocatalyst. The combination shows a synergistic effect for boosting the photocatalytic degradation of a representative antibiotic, lincomycin, both in the degradation rate and the degree of decomposition. In comparison with the intrinsic g/C₃N₄, the structurally optimized photocatalyst shows a tenfold enhancement in degradation rate. Interestingly, various methods and experiments demonstrate the specific catalytic mechanisms for the multiple systems of g/C₃N₄‐based photocatalysts. In the degradation, the active species, including ·O₂^?, ·OH, and h⁺, have different contributions in the different photocatalysts. The intermediate, H₂O₂, plays an important role in the photocatalytic process, and the detailed functions and originations are clarified for the first time.     

g‐C3N4 Loading Black Phosphorus Quantum Dot for Efficient and Stable Photocatalytic H2 Generation under Visible Light

Black phosphorus (BP) is an interesting two‐dimensional material with low‐cost and abundant metal‐free properties and is used as one cocatalyst for photocatalytic H₂ production. However, the BP quantum dot (BPQD) is not studied. Herein, for the first time, BPQD is introduced as a hole‐migration cocatalyst of layered g‐C₃N₄ for visible‐light‐driven photocatalytic hydrogen generation. A high‐vacuum stirring method is developed for BPQD loading without the dissociation of BP. The layered BPQD is coupled on the layered g‐C₃N₄ surface to form a heterojunction structure. The 7% BPQD–C₃N₄ samples show similar time‐resolved photoluminescence curves as 0.5% Pt–C₃N₄. The optimum hydrogen rates of the modified sample (7% BPQD–C₃N₄) are 190, 133, 90, and 10.4 µmol h^?1 under simulated sunlight, LED‐405, LED‐420, and LED‐550 nm irradiation, respectively, which are 3.5, 3.6, and 3 times larger than that of the pristine g‐C₃N₄. Such low‐cost layered system not only optimizes the optical, electrical, and texture properties of the hybrid materials for photocatalytic water splitting to generate hydrogen but also provides ideas for designing novel or easily oxidized candidates by incorporating different available materials with given carriers.     

In Situ Photosynthesis of an MAPbI3/CoP Hybrid Heterojunction for Efficient Photocatalytic Hydrogen Evolution

Halide perovskite like methylammonium lead iodide perovskite (MAPbI₃) with its prominent optoelectronic properties has triggered substantial concerns in photocatalytic H₂ evolution. In this work, to attain preferable photocatalytic performance, a MAPbI₃/cobalt phosphide (CoP) hybrid heterojunction is constructed by a facile in situ photosynthesis approach. Systematic investigations reveal that the CoP nanoparticle can work as co‐catalyst to not only extract photogenerated electrons effectively from MAPbI₃ to improve the photoinduced charge separation, but also facilitate the interfacial catalytic reaction. As a result, the as‐achieved MAPbI₃/CoP hybrid displays a superior H₂ evolution rate of 785.9 µmol h^?1 g^?1 in hydroiodic acid solution within 3 h, which is ≈8.0 times higher than that of pristine MAPbI₃. Furthermore, the H₂ evolution rate of MAPbI₃/CoP hybrid can reach 2087.5 µmol h^?1 g^?1 when the photocatalytic reaction time reaches 27 h. This study employs a facile in situ photosynthesis strategy to deposit the metal phosphide co‐catalyst on halide perovskite nanocrystals to conduct photocatalytic H₂ evolution reaction, which may stimulate the intensive investigation of perovskite/co‐catalyst hybrid systems for future photocatalytic applications.     

Spatially Separated CdS Shells Exposed with Reduction Surfaces for Enhancing Photocatalytic Hydrogen Evolution

To the photocatalytic H₂ evolution, the exposure of a reduction surface over a catalyst plays an important role for the reduction of hydrogen protons. Here, this study demonstrates the design of a noble‐metal‐free spatially separated photocatalytic system exposed with reduction surfaces (MnO_x @CdS/CoP) for highly solar‐light‐driven H₂ evolution activity. CoP and MnO_x nanoparticles are employed as the electron and hole collectors, which are selectively anchored on the outer and inner surface of CdS shells, respectively. Under solar light irradiation, the photogenerated holes and electrons can directionally move to the MnO_x and CoP, respectively, leading to the exposure of a reduction surface. As a result, the H₂ evolution increases from 32.0 to 238.4 µmol h^?1, which is even higher than the activity of platinum‐loaded photocatalyst (MnO_x @CdS/Pt). Compared to the pure CdS with serious photocorrosion, the MnO_x @CdS/CoP maintains a changeless activity for the H₂ evolution and rhodamine B degradation, even after four cycles. The research provides a new strategy for the preparation of spatially separated photocatalysts with a selective reduction surface.     

Exceptional Catalytic Nature of Quantum Dots for Photocatalytic Hydrogen Evolution without External Cocatalysts

The catalytic nature of semiconducting quantum dots (QDs) for photocatalytic hydrogen (H₂) evolution can be thoroughly aroused, not because of coupling with external cocatalysts, but through partially covering controlled amount of ZnS shell on the surface. Specifically, CdSe QDs, with an optimal coverage of ZnS (≈46%), can produce H₂ gas with a constant rate of ≈306.3 ± 21.1 µmol mg^?1 h^?1 during 40 h, thereby giving a turnover number of ≈(4.4 ± 0.3) × 10⁵, which is ≈110‐fold to that of unmodified CdSe QDs under identical conditions. The performance of H₂ evolution is comparable to or even better than the commonly used external cocatalysts, e.g., metal complexes, noble metals assisted photosystems. Mechanistic insights indicate that the dramatically enhanced activity and stability of bare QDs for photocatalytic H₂ production are derived from (i) inhibiting exciton annihilation at trap states, (ii) preventing the photo‐oxidation of core frameworks, and (iii) retaining tunneling efficiencies of photogenerated electrons and holes to reactive sites with partial ZnS coverage.     

Facile “Spot‐Heating” Synthesis of Carbon Dots/Carbon Nitride for Solar Hydrogen Evolution Synchronously with Contaminant Decomposition

The use of solar energy to produce the clean hydrogen (H₂) energy from water splitting is a promising means of renewable energy conversion. High activation barriers for O₂ generation associated with the rate‐limiting steps require utilization of noble metal‐based cocatalysts, which complicates the fabrication procedure and compromises the stability of the catalyst. Here, a homogenous “spot heating” approach is designed via the ultrasonic cavitation effect for evenly embedding highly crystalline carbon quantum dots (CQDs) on 2D C₃N₄ nanosheets. Based on density functional calculations and electrochemical experiments, the optimal introduction of CQDs into C₃N₄ not only extends light absorption spectrum, but also reduces effective mass of electrons (e^?), facilitating photocarrier transport from excited sites. And, more importantly, the well‐organized CQDs with superior peroxidase mimetic activity can increase catalytic H₂ production through the process of (i) 2H₂O → H₂O₂ + H₂; (ii) H₂O₂→2 ? OH; (iii) ?OH + bisphenol A→ Final Products, with H₂ production rate (152 µmol g^?1 h^?1) several times higher than that for pure C₃N₄. This work demonstrates an ideal platform for efficient H₂ production with synergetic organic contaminant degradation, thereby opening possibilities for coupling energy conversion with environmental remediation.     

Refining Energy Levels in ReS2 Nanosheets by Low‐Valent Transition‐Metal Doping for Dual‐Boosted Electrochemical Ammonia/Hydrogen Production

Electrocatalytic nitrogen reduction reaction (NRR) and hydrogen evolution reaction (HER) are intriguing approaches to nitrogen fixation and hydrogen production under ambient conditions, given the need to discover efficient and stable catalysts to light up the “green chemistry” future. However, bottlenecks are often found during N₂/H₂O activation, the very first step of NRR/HER, due to energetic electron injection from the surface of electrocatalysts. It is reported that the bottlenecks for both NRR and HER can be tackled by engineering the energy level via low‐valent transition‐metal doping, simultaneously, where rhenium disulfide (ReS₂) is employed as a model platform to prove the concept. The doped low‐valent transition‐metal domains (e.g., Fe, Co, Ni, Cu, Zn) in ReS₂ provide more active sites for N₂/H₂O chemisorption and electron transfer, not only weakening the N?N/O? H bonds for easier dissociation through proton coupling, but also elevating d‐band center toward the Fermi level with more electron energy for N₂/H₂O reduction. As a result, it is found that iron‐doped ReS₂ nanosheets wrapped nitrogen‐doped carbon nanofiber (Fe‐ReS₂@N‐CNF) catalyst exhibits superior electrochemical activity with eightfold higher ammonia production yield of 80.4 µg h^?1 mg^?1_cat., and lower onset overpotential of 146 mV and Tafel slope of 63 mV dec^?1, when comparing with the pristine ReS₂.     

Localized Surface Plasmon Resonance Enhanced Photocatalytic Hydrogen Evolution via Pt@Au NRs/C3N4 Nanotubes under Visible‐Light Irradiation

Au nanorods (NRs) decorated carbon nitride nanotubes (Au NRs/CNNTs) photocatalysts have been designed and prepared by impregnation–annealing approach. Localized surface plasmon resonance (LSPR) peaks of Au NRs can be adjusted by changing the aspect ratios, and the light absorption range of Au NRs/CNNTs is extended to longer wavelength even near‐infrared light. Optimal composition of Pt@Au NR₇₆₉/CNNT₆₅₀ has been achieved by adjusting the LSPR peaks of Au NRs and further depositing Pt nanoparticles (NPs), and the photocatalytic H₂ evolution rate is 207.0 µmol h^?1 (20 mg catalyst). Preliminary LSPR enhancement photocatalytic mechanism is suggested. On one hand, LSPR of Au NRs is beneficial for visible‐light utilization. On the other hand, Pt NPs and Au NRs have a synergetic enhancement effect on photocatalytic H₂ evolution of CNNTs, in which the local electromagnetic field can improve the photogenerated carrier separation and direct electron transfer increases the hot electron concentration while Au NRs as the electron channel can well restrain charge recombination, finally Pt as co‐catalyst can boost H⁺ reduction rate. This work provides a new way to develop efficient photocatalysts for splitting water, which can simultaneously extend light absorption range and facilitate carrier generation, transportation and reduce carrier recombination.     

CuCo Bimetallic Oxide Quantum Dot Decorated Nitrogen‐Doped Carbon Nanotubes: A High‐Efficiency Bifunctional Oxygen Electrode for Zn–Air Batteries

The large‐scale production of metal–air batteries, an appealing solution for next‐generation energy storage, requires low‐cost, earth‐abundant, and efficient oxygen electrode materials, yet insights into active catalyst structures and synergistic reactivity remain largely unknown. Here, a new bifunctional oxygen electrode based on nitrogen‐doped carbon nanotubes decorated by spinel CuCo₂O₄ quantum dots (CuCo₂O₄/N‐CNTs) is reported, outperforming the benchmark of state‐of‐the‐art noble metal catalysts. Combining spectroscopic characterization and electrochemical studies, a prominent synergetic effect between CuCo₂O₄ and N‐doped carbon nanotubes is uncovered: the high conductivity, large active surface area, and increase in the number of catalytic sites induced by Cu doping (i.e., Cu²⁺ and Cu?N) can be beneficial to the overall electrocatalytic activities. Remarkably, the native flexibility of CuCo₂O₄/N‐CNTs allows its direct use as reversible oxygen electrodes in Zn–air batteries either with liquid alkaline electrolyte or in the all‐solid‐state configuration. The prepared devices demonstrate excellent discharging/charging performance, large energy density (83.83 mW cm^?2 in liquid state, 1.86 W g^?1 in all‐solid‐state), and long lifetime (48 h in liquid state, 9 h in all‐solid‐state), holding great promise in the practical application of rechargeable metal–air batteries and other fuel cells.     

Coupling Piezocatalysis and Photocatalysis in Bi4NbO8X (X = Cl,Br) Polar Single Crystals

Reactive oxygen species (ROS) as green oxidants are of great importance for environmental and biological applications. Photocatalysis is one of the major routes for ROS evolution, which is seriously restricted by rapid charge recombination. Herein, piezocatalysis and photocatalysis (i.e., piezo–photocatalysis) are coupled to efficiently produce superoxide radicals (?O₂^?), hydrogen peroxide (H₂O₂), and hydroxyl radicals (?OH) via oxygen reduction reaction (ORR), by using Bi₄NbO₈X (X = Cl, Br) single crystalline nanoplates. Significantly, the piezo‐photocatalytic process leads to the highest ORR performance of the Bi₄NbO₈Br nanoplates, exhibiting ?O₂^?, H₂O₂, and ?OH evolution rates of 98.7, 792, and 33.2 µmol g^?1 h^?1, respectively. The formation of a polarized electric field and band bending allows directional separation of charge carriers, promoting the catalytic activity. Furthermore, the reductive active sites are found enriched on all the facets in the piezo–photocatalytic process, also contributing to the ORR. By piezo–photodeposition of Pt to artificially plant reductive reactive sites, the Bi₄NbO₈Br plates demonstrate largely enhanced photocatalytic H₂ production activity with a rate of 203.7 µmol g^?1 h^?1. The present work advances piezo–photocatalysis as a new route for ROS generation, but also discloses the potential of piezo–photocatalytic active sites enriching for H₂ evolution.     

Delocalized Electron Accumulation at Nanorod Tips: Origin of Efficient H2 Generation

Photocatalytic hydrogen (H₂) evolution requires efficient electron transfer to catalytically active sites in competition with charge recombination. Thus, controlling charge‐carrier dynamics in the photocatalytic H₂ evolution process is essential for optimized photocatalyst nanostructures. Here, the efficient delocalization of electrons is demonstrated in a heterostructure consisting of optimized MoS₂ tips and CdS nanorods (M‐t‐CdS Nrs) synthesized by amine‐assisted oriented attachment. The heterostructure achieves photocatalytic H₂ activity of 8.44 mmol h^?1 g^?1 with excellent long‐term durability (>23 h) without additional passivation under simulated solar light (AM 1.5, 100 mW cm^?2). This activity is nearly two orders of magnitude higher than that of pure CdS Nrs. The impressive photocatalytic H₂ activity of M‐t‐CdS Nrs reflects favorable charge‐carrier dynamics, as determined by steady‐state PL and time‐correlated single photon counting correlation analysis at low temperature. The MoS₂ cocatalysts precisely located at the end of the CdS Nrs exhibit ultrafast charge transfer and slow charge recombination via spatially localized deeper energy states, resulting in a highly efficient H₂ evolution reaction in lactic acid containing an electrolyte.     

In Situ Bond Modulation of Graphitic Carbon Nitride to Construct p–n Homojunctions for Enhanced Photocatalytic Hydrogen Production

Graphitic carbon nitride (g‐C₃N₄) has recently emerged as an attractive photocatalyst for solar energy conversion. However, the photocatalytic activities of g‐C₃N₄ remain moderate because of the insufficient solar‐light absorption and the fast electron–hole recombination. Here, defect‐modified g‐C₃N₄ (DCN) photocatalysts, which are easily prepared under mild conditions and show much extended light absorption with band gaps decreased from 2.75 to 2.00 eV, are reported. More importantly, cyano terminal C?N groups, acting as electron acceptors, are introduced into the DCN sheet edge, which endows the DCN with both n‐ and p‐type conductivities, consequently giving rise to the generation of p–n homojunctions. This homojunction structure is demonstrated to be highly efficient in charge transfer and separation, and results in a fivefold enhanced photocatalytic H₂ evolution activity. The findings deepen the understanding on the defect‐related issues of g‐C₃N₄‐based materials. Additionally, the ability to build homojunction structures by the defect‐induced self‐functionalization presents a promising strategy to realize precise band engineering of g‐C₃N₄ and related polymer semiconductors for more efficient solar energy conversion applications.     

Graphene‐Like Carbon Nitride Nanosheets for Improved Photocatalytic Activities

“Graphitic” (g)‐C₃N₄ with a layered structure has the potential of forming graphene‐like nanosheets with unusual physicochemical properties due to weak van der Waals forces between layers. Herein is shown that g‐C₃N₄ nanosheets with a thickness of around 2 nm can be easily obtained by a simple top‐down strategy, namely, thermal oxidation etching of bulk g‐C₃N₄ in air. Compared to the bulk g‐C₃N₄, the highly anisotropic 2D‐nanosheets possess a high specific surface area of 306 m² g^?1, a larger bandgap (by 0.2 eV), improved electron transport ability along the in‐plane direction, and increased lifetime of photoexcited charge carriers because of the quantum confinement effect. As a consequence, the photocatalytic activities of g‐C₃N₄ nanosheets have been remarkably improved in terms of ?OH radical generation and photocatalytic hydrogen evolution.     

Tuning the Catalytic Preference of Ruthenium Catalysts for Nitrogen Reduction by Atomic Dispersion

Developing cost‐effective, high‐performance nitrogen reduction reaction (NRR) electrocatalysts is required for the production of green and low‐cost ammonia under ambient conditions. Here, a strategy is proposed to adjust the reaction preference of noble metals by tuning the size and local chemical environment of the active sites. This proof‐of‐concept model is realized by single ruthenium atoms distributed in a matrix of graphitic carbon nitride (Ru SAs/g‐C₃N₄). This model is compared, in terms of the NRR activity, to bulk Ru. The as‐synthesized Ru SAs/g‐C₃N₄ exhibits excellent catalytic activity and selectivity with an NH₃ yield rate of 23.0 µg mg_cat^?1 h^?1 and a Faradaic efficiency as high as 8.3% at a low overpotential (0.05 V vs the reversible hydrogen electrode), which is far better than that of the bulk Ru counterpart. Moreover, the Ru SAs/g‐C₃N₄ displays a high stability during five recycling tests and a 12 h potentiostatic test. Density functional theory calculations reveal that compared to bulk Ru surfaces, Ru SAs/g‐C₃N₄ has more facile reaction thermodynamics, and the enhanced NRR performance of Ru SAs/g‐C₃N₄ originates from a tuning of the d‐electron energies from that of the bulk to a single‐atom, causing an up‐shift of the d‐band center toward the Fermi level.     

Bifunctional Hydrogen Production and Storage on 0D–1D Heterojunction of Cd0.5Zn0.5S@Halloysites

Development of efficient solar‐driven hydrogen (H₂) evolution and H₂ storage materials is challenging. Sulfide nanocatalysts show large potential for H₂ production, but suffer from the drawbacks of inefficient charge separation, serious photocorrosion, and easy agglomeration. Herein, a 0D–1D satellite‐core ethylenediaminetetraacetic acid (EDTA)‐bridged Cd_0.5Zn_0.5S@halloysite nanotubes tertiary structure is designed via facile in situ assembly, which settles all the above‐mentioned issues and achieves exceptional and stable photocatalytic H₂ evolution and storage. Significantly, EDTA grafted on halloysites as the hole (h⁺) traps steers the photogenerated h⁺ and electrons (e^?) from Cd_0.5Zn_0.5S separately to halloysites and outer surface Pt sites, achieving efficient directional separation between h⁺ and e^? and inhibiting the h⁺‐dominated photocorrosion occurring on Cd_0.5Zn_0.5S. Benefiting from these advantages, the hierarchy shows an unprecedented photocatalytic H₂ evolution rate of 25.67 mmol g^?1 h^?1 with a recording apparent quantum efficiency of 32.29% at λ = 420 nm, which is seven‐fold that of Cd_0.5Zn_0.5S. Meanwhile, an H₂ adsorption capacity of 0.042% is achieved with the room temperature of 25 °C and pressure of 2.65 MPa. This work provides a new perspective into designing hierarchical structure for H₂ evolution, and proposes an integration concept for H₂ evolution and storage.     

Efficient Photocatalytic Nitrogen Fixation: Enhanced Polarization,Activation, and Cleavage by Asymmetrical Electron Donation to NN Bond

Photocatalytic nitrogen (N₂) fixation suffers from low efficiency due to the difficult activation of the strongly nonpolar N?N bond. In this study, a Ru–Co bimetal center is constructed at the interface of Ru/CoS_x with S‐vacancy on graphitic carbon nitride nanosheets (Ru‐Vs‐CoS/CN). Upon adsorption, the two N atoms in N₂ are bridged to the Ru–Co center, and the asymmetrical electron donation from Ru and Co atoms to N₂ adsorbate highly polarized N?N bond to double bond order. The plasmonic electric‐field‐enhancement effect enables the Ru/CoS_x interface to boost the generation of energetic electrons. The Schottky barrier between Ru and CoS_x endows the interface with electron transfer from CoS_x to Ru. The Ru‐end bound N at the Ru–Co center is preferentially hydrogenated. As a result, the Ru‐Vs‐CoS/CN photocatalyst shows an NH₃ production rate of up to 0.438 mmol g^?1 h^?1, reaching a high apparent quantum efficiency of 1.28% at 400 nm and solar‐to‐ammonia efficiency of 0.042% in pure water under AM1.5G light irradiation.     

Targeted Exfoliation and Reassembly of Polymeric Carbon Nitride for Efficient Photocatalysis

Switching the properties of photocatalytic materials targetedly and exerting these advantages fully in different photoredox reactions are crucial for the sufficient utilization of solar energy but still presents a significant challenge. This study presents a facile, green, and reversible exfoliation–reassembly strategy to switch the features of polymeric carbon nitride (CN) favorably for different photoredox reactions. The giant expansion effect of in situ‐generated H₂O molecules confined to the interlayer results in the mass production of ultrathin polymeric CN nanosheets, giving a high yield, i.e., up to 48%, of ultrathin nanosheets in a mild solution (pH ≈1.3). Interestingly, the exfoliation–reassembly process as well as the properties of CN are largely reversible via alternating the interlayer groups. Moreover, the exfoliated and reassembled CN achieve a superior photocatalytic activity for isopropanol degradation (acetone: 345 µmol h^?1; CO₂: 23 µmol h^?1) and H₂ evolution (1370 µmol h^?1), resulting in a high apparent quantum yield of 27% and 46%, respectively, at ≈420 nm.